The present invention relates to a lens-fitted photographic film unit including a electronic flash unit by which a previously charged unexposed film can be immediately subjected to flash photography, and more particularly relates to a lens-fitted photographic film unit including a electronic flash unit having a a printed board on which a electronic flash circuit is formed and also having a electronic flash trigger switch capable of being used as a sector spring for a sector to expose the film for a period of time.
In this specification, the lens-fitted photographic film unit is defined as a camera integrally provided with a photographic film, and this camera is used only when the previously charged photographic film is exposed for photography, and the camera body is recycled after the charged photographic film has been exposed and taken out from the camera.
FIG. 9 is a perspective view showing an external appearance of a conventional lens-fitted photographic film unit, wherein the view is taken from the back of the lens-fitted photographic film unit.
Operations of the conventional film unit from the sector charge to the film exposure will be explained below.
When a sector 66 pivotally supported by a sector pin 18D implanted in the film unit body 10 is operated, a sector lever 65 conducts an exposing operation so that an image formed by a photographic lens (not shown) is exposed on a photographic film.
A sector drive pin 65A is implanted in the sector lever 65 and inserted into a forked portion of the sector 66. A pin 18B is inserted into a long hole of the sector lever 65, so that the sector lever 65 can be slidably guided by the pin 18B. When a sector spring 67 is provided between an engaging member 65C implanted in the sector lever 65 and a pin 18C implanted in the film unit body 10, the sector lever 65 is pushed in a direction in such a manner that the left side of the long hole of the sector lever 65 comes into contact with the pin 18B. The sector lever 65 is provided with a rising portion 65B and an arm plate 65D. In this case, the arm plate 5D is pushed by the sector spring 67 in a direction in such a manner that the arm plate 65D comes into contact with the pin 8C implanted in the film unit body 10. The sector lever 65 is vertically regulated by a holding plate (not shown) provided in a sector case (not shown) attached to the film unit body 10, so that the sector lever 65 is not disengaged from the pin 18B.
A triangular kick member 61C is provided at the middle of an arm portion 61B of the charge lever 61. When the charge lever 61 is rotated clockwise, the rising portion 65B of the sector lever 65 pushes the kick member 61C. Due to the foregoing, the sector lever 65 is moved onto the sector 66 side while the long hole of the sector lever 65 is guided by the pin 18B, resisting a tension force of the spring 67. When the sector lever 65 is moved as described above, the sector drive pin 65A of the sector lever 65 is moved in the forked portion of the sector 66 without moving the sector 66 from its closing position. When the charge lever 61 is rotated clockwise, the kick member 61C of the charge lever 61 is disengaged from the rising portion 65B of the sector lever 65. Then the sector lever 65 is returned by a spring force to a position at which the left end of the long hole of the sector lever 65 comes into contact with the pin 18B, and the arm plate 65D of the sector lever 65 comes into contact with the pin 18C. In this condition, the sector charge mechanism 60 completes the charging operation.
As described above, not only the sector spring 67 returns the sector lever 65 but also the sector spring 67 always rotates the sector lever 65 around the pin 18B counterclockwise. By the counterclockwise rotating motion of the sector lever 65, the time of exposure conducted by the sector 66 is determined in relation to a charge lever spring 64 which is stronger than the sector spring 67. Even when the sector lever 65 is moved while the long hole is guided by the pin 18B, the sector drive pin 65A of the sector lever 65 always holds the sector 66 in a closed condition.
The electronic flash unit 40 is constructed in the following manner:
The electronic flash circuit is provided on a printed board 41, and a electronic flash light emitting unit 140 and a contact point unit 44C having a pair of synchronizing contacts 44A, 44B are integrally provided on the printed board 41. After the electronic flash unit 40 has been attached to the film unit body 10, it is electrically connected so that electronic flash light emitting control can be conducted. PA1 A winding stopper 57 is pushed in a direction of an arrow put on a winding knob 51. The winding stopper 57 is rotated counterclockwise resisting a spring force of a winding stopper spring 58. An edge of an arm portion 61A of the charge lever 61 is disengaged from an end surface of an arm portion 57A of the winding stopper 57. Therefore, a cam stopper 62 is rotated counterclockwise by a spring force of the charge lever spring 64.
Exposure conducted on a film will be explained as follows.
When a release button (not shown) on a front cover (not shown) is pressed, the operation is conducted as follows:
When the charge lever 61 is rotated counterclockwise by a spring force of the charge lever spring 64 which is stronger than the sector spring 67, the triangular kick member 61C attached to the charge lever 61 hits the rising portion 65B of the sector lever 65, so that the rising portion 65B is disengaged from the kick member 61C. Due to the foregoing, the sector lever 65 is rotated clockwise around the pin 18B in the long hole, resisting a tension generated by the sector spring 67. Accordingly, a pushing portion 65G provided at a fore end of the arm plate 65D of the sector lever 65 pushes a electronic flash trigger switch 44A. Due to the foregoing motion, the synchronizing contacts 44B and 44C are contacted with each other. When the synchronizing contacts 44B and 44C are contacted in the manner described above, electric power is supplied from a condenser (not shown) to the electronic flash light emitting section, so that electronic flash light is emitted. During the electronic flash light is emitted, the sector 66 rotates to expose the photographic film. Successively, the sector lever 65 is returned to its initial position by a tension of the sector spring 67. Consequently, the sector drive pin 65A rotates the sector 66 around the sector pin 18D so as to expose the photographic film, and then the sector 66 is closed.
As described above, the sector spring 67 composed of a coil spring acts on the sector 66 to hold a light-tightly closed position before shutter release operation, and acts on the sector 66 to return to its initial light-tightly closed position after shutter release operation and its consequent swing motion. When the sector spring 67 is provided between the sector lever 65 and the film unit body 10, or between the sector 66 and the film unit body 10, a difference is caused in the swing speed of the sector 66 by the existence of a printed board described later, so that an error is caused in the shutter speed. The reason why the error is caused is that the electronic flash trigger switch 44A becomes a load for the sector spring 67. In order to solve the above problems, there are provided two types of sector springs 67 in which the pushing forces are different. One is a sector spring suitable for a device in which a printed board for electronic flash use is provided, and the other is a sector spring suitable for a device in which a printed board for electronic flash use is not provided. When the above sector springs having different pushing forces are appropriately used, the occurrence of an error of the shutter speed is prevented.
According to the above construction, the number of parts is large. Further, at least two types of coil springs must be prepared, and one of them must be appropriately selected for assembly. Therefore, the assembly process becomes complicated.